Blackboard-rubber



(No Model.)

G. E. GREGORY. BLAGKBOARD RUBBER.

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UNITED STATES PATENT OFFICE.

CHARLES EZRA GREGORY, OE NASHVILLE, TENNESSEE.V

.BLACKBOARD-RUBBER.

SPECIFICATION forming part of Letters Patent No. 570,797, dated November3, 1896.

Application filed March 9, 1896.

To @ZZ whom it may concern:

Be it known that I, CHARLES EZEA GREG- ORY, a citizen of the UnitedStates, residing at Nashville, in the county of Davidson and State ofTennessee, have invented certain new and usefullmprovements inBlackboard- Rubbers; and l do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

The object of my said invention is to provide an eraser for blackboards,or a blackboard-rubber, which, while being very efficient for thepurpose, inexpensive to'manufacture, and of great durability, will alsobe entirely non-resonant in its character, thus providing against thecommon annoyance consequent upon the continual accidental dropping oferasers by users thereof upon furniture and the floor in school-roomsand other places, and the disturbance caused thereby; and it consists invarious improvements in the details of construction whereby theseobjects are accomplished, as will be hereinafter more fully describedand claimed.

Referring to the accompanying drawings, which are made a part hereof,and on which similar letters of reference indicate similar parts, Figure1 is a perspective view of one of my improved erasers or rubbers, andFig. 2 a cross-section through the same.

Said eraser is composed entirely of nonresonant material, preferablyfelt, which has been found to be very desirable for the purpose. Itsback is shown as composed of two pieces A and A', stitched together,(the number of pieces is, of course, not material,)a label a, composedof soft material, as kid, soft leather, paper, or cloth, being alsopreferably secured thereto by the same stitches for containing theadvertising-matter of the manufacturer, instructions for using, ctc. Theback thus made up furnishes suiicient rigidity and stiffness for thepurpose without containing any substance which will make a noise whenbrought into forcible contact with hard substances, such as when droppedupon a floor.

The face of the eraser is also composed of suitable non-resonantmaterial, preferably felt, cut into strips or pieces o f suitable dimen-Serial No. 582,428. (No model.)

sions and placed face to face to make up the block desired, which issecured to said back at one of the sides composed of the edges of thestrips, the opposite side forming the operating-face of the eraser orrubber. In the drawings said face is shown as composed of five strips offelt, the central one a' being of considerably greater thickness thanthe 6o other strips and thicker on its face than at its back to giveshape to the block. On each side of said strip is a strip a2, and on theouter face of each of said strips another strip a3; but, as will bereadily understood, 65 the number of strips may be greater or less, asdesired, it being only essential that the rubbing-face be composed of amultiple of strips, as` will be presently described. Said several stripscomposing the rubbing-face of 7o the eraser are secured together by glueor adhesive material of suitable character, which is placed betweentheir contiguous faces from their back edges to a point near their edgesforming the face of the eraser, but not eX- tending entirely to saidface, it being desired to leave the several edges free at this side toprovide channels or recesses in the operating face to take up thecrayon-dust.

The block comprising the several strips and 8o constituting the face ofthe eraser is secured to the back by glue or adhesive material. Saidglue is indicated in the drawings by the heavy black lines anddesignated by the reference-letter a4. Said glue is of a character or 85 consistency that while it will secure the parts together withsufficient firmness yet will allow the front edges of the stripscomposing the rubbing-face to gradually separate under the strain ofusage as they wear away, thus 9o maintaining the channels between saidstrips at this point for the purpose mentioned. Should such result notfollow from usage in any case the desired separation could be forciblyeffected, of course.

By constructing an eraser as thus described, l with its rubbing-facecomposed of a number of strips set with their edges forming the'operating-face and arranged so as to provide the channels in said face,an eraser is proroo vided which will, in operation, quickly `andthoroughly clean a blackboard, the dust being taken up in the channelsin its face, which because of their peculiar character and for= mation,retain the same until forcibly removed, which can be readilyaccomplished by rapping the eraser or using a brush, or by both methods.By forming it entirely of non-resonant material it may be dropped aboutin the school-room or other places where used Without causing anydisturbance, and because of being composed of such material and havingits parts connected by a glue of the character named the eraser can beused until it is Worn entirely to the back, thus adding materially toits life, and consequently to its value, and also avoiding the danger ofscratching the board and injuring it, as is often done by the use ofordinary erasers, the rubbing-surface of Which soon becomes Worn to thehard back which then comes against the board surface to its greatinjury.

Having thus fully described my said invention, What I claim as new, anddesire to secure by Letters Patent, is-

1. A blackboard-rubber consisting of a back and several strips securedthereto to form the face, Which strips are arranged With their edges toform the rubbing-face, their contiguous faces being joined to each otherby adhesive material to a point not quite to said face, wherebylongitudinal Ways or channels with open ends are provided in said faceto take up the chalk-dust, substantially as set forth.

2. A blackboard-rubber having a face composed of strips of materialsecured together to a point near their edges Which constitute therubbing-face by an adhesive material of a character which will permit oftheir gradual separation, substantially as set forth.

3. A blackboard-rubber, consisting of a back of non-resonant material,and a rubbingface secured thereto by adhesive material, whichrubbing-face is composed of strips of similar material arranged Withtheir edges to form the operating-face and stuck to each other withadhesive material, substantially as set forth.

In testimony whereof I aiiix my signature in presence of two Witnesses.

XV. E. METZGER, GRACE DAWSON.

